Addressable electrical units for receiving address coded signals have a variety of uses relating to smoke, fire and burglar detector systems. In each such system, there is a central control which transmits address coded electronic signals to remote sensors or electrical units, each unit having its own address. Thus, the central control can communicate selectively with each remote unit for a variety of purposes including testing of the units, locating the address of a sensor that has been triggered, detecting removal of a unit, etc.
Such systems for use with fire detectors and smoke detectors are described in U.S. Pat. Nos. 5,117,219 (Tice) and 4,829,283 (Spang), which are incorporated by reference herein.
There are several known methods for setting the address of a remote electrical unit which receives address coded signals. One known method is to place an addressable receiver for receiving address coded signals in a mounting base which holds a detachable sensor unit. The mounting base has a mechanical or electronic means for setting the address of the receiver. Thus, the central control unit correlates the address code with the mounting base. This method has the disadvantage of requiring maintenance of mechanical and electrical components located in the mounting base which may be difficult to access.
A second method includes locating the receiver and its addressable portion in the detachable sensor unit instead of the mounting base. This avoids the problem of having to maintain mechanical and electronic components located in the mounting base.
A disadvantage of such a system is that the addressable detachable unit may be removed from its mounting base and inadvertently placed into a different mounting base at a different location. Thus, the location of the sensor unit is changed while the address in the receiver inside the sensor unit remains unchanged. It would be desirable to prevent this inadvertent misplacement of the unit.
There continues to be a need for a detachable sensor unit having an addressable receiver and a mounting base having a means for verifying the address of the detachable unit to prevent misplacement of the unit.